This invention relates to logarithmic amplifiers, and more particularly, to logarithmic amplifiers wherein the gain is easily changed to accomodate a range of input signal currents. Logarithmic amplifiers are used in applications where there is a need to compress an input having a large dynamic range into an output having a small dynamic range. However, in prior art logarithmic amplifiers, the linear gain factor imposed on the logarithmic output voltage was either a fixed function or not easily changed. What is desired is a logarithmic amplifier having an easily changible gain in order that a range of input signal currents may be accomodated and in order that the dynamic range requirements of linear amplifiers following the logarithmic amplifier may be relaxed.